This invention comprises a free floating carrier for deep well instruments and more generally pertains to a system for conveying deep well testing and recording instruments in a well bore to a selected region to be tested, obtaining test data by said instruments and then returning the instruments to the surface through the well bore for retrieving the test data obtained thereby, all in an automatic manner controlled from the surface.
It is frequently desirable to obtain precise test data as to conditions in selected regions in a well bore by conveying testing and/or recording instruments through the well bore to the selected region, conducting the test and recording the test data, and then returning the instruments to the surface where the data may be retrieved and used in various manners. Heretofore, it has been necessary to transport instruments in a well bore through the agency of wire lines, or attaching the instruments to rod or pipe strings or the like. Such methods have been unwieldy and cumbersome, requiring the use of or manipulation of relatively long mechanical instrument supporting and handling lines or strings, and have been relatively time consuming while also in some instances detrimentally affecting the condition of the well bore by the movement of the instruments through the fluid in the well bore.
Under the conventional method of introducing and withdrawing instruments from a well bore by the use of wire lines, it is necessary to discontinue the mud circulation in the hole for varying periods of time, as for example, thirty minutes to an hour or more. This results in a diminution of the protective mud pressure against the walls of the well bore, producing a dangerous or hazardous condition. Further, during the wire line manipulation of the instruments, the well head is necessarily open, for the wire line to work through, preventing the application of pressure from the pump or the maintenance of pressure in the well bore as a precaution against blow outs from high pressure zones while the instruments are being employed.